Drawing FIG. 1 schematically depicts a typical prior art center-pivot sprinkler irrigation apparatus (200) including a lengthy water distributing conduit (210) having some elevation above the earth "E" and having water outlets (209). At the land tract "E" central site (300V) there is a central-pillar assembly 100 including water delivery means ultimately flowing into the conduit(210) inward-end 211. The water delivery means commences at inflow-pipe 100W and proceeds therefrom along medial-piping 202 to conduit inward-end 211. The typical water distributing conduit 210 extends radially outwardly from geographical vertical-reference 300V, there being underlying traction supports (S1, S2 . . . S(N-1), SN) spaced therealong. Since the water inflow-pipe 100W usually emanates from terrain "E" below conduit 210, conduit inward-end 211 necessarily derives water from some outflow-elbow means (e.g. 105, 20) located loftily above terrain "E". Thus, as lengthy water distributing conduit 210 travels overland around its center-pivot (300V) inward-end 211, its far-end 218 circumscribes an irrigatable geometric shape 300S surrounding center-pivot 300V.
As schematically indicated in FIG. 1, electrical cable means (220) comprising a plurality of parallel electrical conductors might be periodically attached (at 225) and extend along the lengthy water distributing conduit 210 to control various functional components of the irrigation apparatus 200. For example, certain conductors (e.g. 221) might control the dual-directional drive motors DM for the respective traction wheels "W" including on-off and forward-reverse; other conductors (e.g. 222) might control the steering of steerable traction wheels "SW"; another conductor (e.g. 223) might control the actuation of end-gun 219; and other conductors (not shown) might control various other apparatus components. Inasmuch as the water distributing conduit 210 and the co-extensive electric cable means 220 rotate around center-axis 300V, there is necessarily an electrical commutation means (e.g. 109) positioned adjacent vertical center-axis 300V to prevent kinking or twisting of the cable means at its juncture with incoming powerline 120. The electrical commutation means has a non-rotatable brush holder portion 109B mounted upon an upright arm extension 108 from central-pillar bracing framework 107, and the commutation means armature portion 109A is physically attached to the cable means for co-rotation around vertical-axis 300V.
The medial-piping 102, surrounding vertical-axis 300V, proceeds upwardly from the water source (100W) coupling terminus 103 to the rotatably connected (101) outflow-elbow means 105. The medial-piping 102 is mounted in upright condition, as by said bracings 107 which are attached to earth-anchoring (e.g. concrete slab "PE"). Thus, such representative central-pillar assemblies 100 comprise various interdependent components which in the prior art require laborious assembling by skilled technicians at the central-pillar site 300V, namely: medial-piping 102, inflow-pipe coupling 103, rotatable coupling 101, outflow-elbow 105, bracing means 107, electrical commutation (109) and support therefor (e.g. 108), and commutation housing. A significant proportion of the working day of these highly-skilled required technicians is spent unproductively in traveling to the geographically remote and scattered farm sites where their expensive services are required. Economic savings would result if such high salaried technicians might spend their entire working day at a single factory type location in building the precision central-pillar assemblies in modular form suitable for transportation to the farm sites and there installed at the center-pivot site (300V) by relatively unskilled personnel. However, the prior art does not suggest a structural relationship of the central-pillar assembly into a precision built modular form that can be shipped from factory to farm site for field installation by relatively unskilled local personnel.